Gun perforator for well casings



Aug. 28, 1951 J. o. Tow v 2,565,788

GUN PERFoRAToR Foa WELL cAsINGs Filed Aug. 25. 1947 2i JAMES 0. TOW

Patented Aug. 28, 1951 :,sssnss e GUN raaromrroa ron WELL cssmcs James 0. Tow, Huntington Park, Calif., assigner to McCullough Tool Company, Los Angeles,

Calif., a corporation of Nevada Application August-23, 1947, Serial No. 710,231

My invention relates to guns employing an explosive for propelling a projectile and relates in particular to perforating guns employed in weils to perforate the well casing by shooting projectiles therethrough.

It is an object of the invention to provide a well perforating gun having a plurality of barrels axially movable in a supporting structure, such as a gun body, and means acting in response to forward movement of the gun barrels relatively to the projectiles to ignite or fire the powder charges.

It is a 'further object of the invention to provide a gun having a movable barrel, with means for holding the projectile so as to restrain or limit movement thereof and means for moving the barrel with relation to the projectile, thereby causing the ring of the powder charge disposed behind the projectile in the barrel. Herein the term powder charge is employed to designate those explosive substances which burn with sui'- ficient rapidity to produce a high gas pressure substantially instantaneously against the rear end of the projectile, or which explode with a detonating action.

It is a further object of the invention to provide a gun having a supporting structure or body in which a gun barrel is supported for axial movement in forward direction, there being walls to provide a recess to receive a charge of explosive which, when exploded, will apply force to the gun barrel to move the same forwardly, and thereby accomplish ignition of the powder charge which lies in the barrel behind the projectile, in the manner described in detail herein.

It is a further object of the invention to provide a gun having a body with a chamber, this chamber having an external opening, there being an axially movable barrel in the chamber and a retainer for holding the barrel in the chamber, this retainer having thereon means for controlling the position of the projectile so that when the barrel is moved forwardly, a relative movement between the barrel and the projectile is accomplished, such relative movement being employed to re the powder charge which lies behind the projectile.

A further object of the invention is to provide a gun of the character herein described, having a channel to receive a priming cord, or equivalent explosive substance, this channel communicating with a space at the rear end of the bar- 8 Claims. (Cl. IBI- 0.5)

rel, so that force from the explosion of the primer cord produces forward movement of the barrel.

A further object of the invention is to provide in a gun oi' the character described herein a sealing means for the barrel which also controls or limits forward movement of the projectile, this sealing means being frangible or removably held so that when the gun is fired, there will be a removal or displacement of the sealing means as the projectile is ejected. A feature of the invention is that this sealing and projectile holding means acts to restrain forward movement of the projectile for a short period of time while gas pressure from the burning of the powder charge builds up behind the projectile, with the result that the projectile is finally expelled from the barrel at high velocity and with great vperforating force.

Further objects and advantages of the invention will be brought out in the following part of the specification, wherein I have described specific details of the invention for the purpose of clearly disclosing the same without placing limitation on the scope of the invention defined in the appended claims.

Referring to the drawings which are for illustrative purposes only,

Fig. 1 is a fragmentary partly sectioned view, showing a gun embodying my present invention.

Fig. 2 is an enlarged cross section taken as indicated by the line 2 2 of Fig. l.

Fig. 3 is a cross sectional view similar to Fig. 2, but showing an alternative form of retaining means.

Fig. 4 is a sectional view similar to Fig. 2, but showing an alternative form oi ignition means for the powder charge.

Fig. 5 is a fragmentary sectional view showing an alternative construction for the projectile controlling or holding member.

In Fig. l I show the lower portion of a gun body I0, this-gun body lli having a spiral channel or recess I i in the surface thereof for receiving a primer cord i2. At the lower end of this spiral recess there is a depression or cavity Il in which a clip Il, held by a screw i5, secures the lower end of the primer cord l2. The use of a primer cord for accomplishing ignition of powder charges in a perforating gun is old and means for igniting the primer cord are well known in the art; accordingly, for simpliilcation of this disclosure, I have not shown the upper end of the gun body lli which contains the means for igniting or exploding the primer cord i2.

The gun body I0 has therein a, plurality of gun barrel receiving chambers I6. These chambers I0 are disclosed as consisting of cylindric bores diametrically reduced at their rear ends so as to form shoulders Il. The rear ends of the chambers I6 are connected through openings I8 with portions of the spiral channel or recess II, the purpose of this arrangement being to utilize the explosive force of the primer cord I2, through the openings I8 to accomplish gun firing functions as will be hereinafter described.

In each of the chambers I6 there is a cylindric gun barrel I9 having a bore 29 leading inward from the front end 2I of the barrel I9. this bore 20 having at its inner end a powder charge 22, andahead of the powder charge 22, a projectile 23. To limit forward movement of the barrel I9, a, retainer 24 is threaded into the opening 25 of the chamber I6. The forward portion or front end 2I of the barrel I9 is of reduced diameter so as to provide an annular shoulderl 25 which confronts and is spaced from the cylindric wall portion 26 of the retainer 24. The retainer 24 has a threaded opening 21 aligned with and slightly larger in diameter than the barrel bore 20. A projectile holding member 2-8 is threaded into the opening 21, this projectile holding member having a portion 29 which extends into the barrel I9 and ,confronts or engages the nose of lthe projectile 23, this holding member 28 oontrolling the forward position of the projectile 23 in that it limits outward movement of the projectile before and up until the time the perforating gun is red. The holding member 28 carries thereon a, seal 3| for sealing the front end of the barrel I9, this seal 3| consisting of a ring of rubber carried in an annular channel 38 formed in the holding member 28. The holding member 2-9 is so formed that when the powder charge 22 is exploded, the member 28 will be removed from its position at the front end of the barrel I9. The holding member 28 is shown as being of hollow form and the metal from which itis formed 'is of such character that the force with which the projectile 23 is propelled outwardly by the ring of the powder charge 22 will result in 9. shearing of the holding member 28 or a disintegration of the same. A feat-ure of this holding member 28 in addition to the functions hereinbefore ascribed thereto, is that it initially restrains outward movement of the projectile 23 when the powder charge 22 is first ignited. The result of this is that a heavy pressure of gaseous products is built up behind the projectile 23, while, at the same time, outward movement of the projectile 2l is restrained until the pressure of the burning powder charge behind the projectile 23 builds up to a. magnitude capable of overcoming the resistance of the plug or holding member 28. When the holding member 28 then yields, the projectile 23 is driven from the barrel-at increased velocity and with great penetrating force.

The firing of the perforating gun is accomplished by igniting and exploding the primer cord I2 in any of the manners well known to the art. Through each of the openings I8. the explosive force of the overlying portion of the primer cord I2 is transmitted to the rear end of the barrel I9, driving such barrel forward, while the holding member 28 prevents forward movement of the projectile 23. 4The forward movement of the barrel I9 causes the rear end wal132 thereof to move toward the rear end of the projectile 23, compressing the powder charge 22 and causing the same to explode by compression and/or detonation.

In Fig 2 I have shown ports 24a in the retainer 24 to permit flow of uid from the space 33 within the retainer 24 adjacent the front end of the barrel I9. In Fig. 3 I show a form of my invention having a cup-like retainer 24' omitting the ports 24a. To provide for escape of fluid from'the space 24bahead of the barrel I9, ports s4 are armed through the body n in positions to communicate with the space 2lb, the plane of communication between the ports 34 and the space 2lb being rearwardly of the inner lip of the retainer 24'. Also, in Fig. 3 I show means for preventing inadver'ent firing of'any of the powder charges 22 in a perforating gun of the type disclosed herein, due to application of a shock or blow tending to shift a gun barrel I9 outwardly in the chamber I9 which holds the same. For this purpose the gun barrel I9 has a depression or socket 35 which receives the inner end of a shear pin 3E which is placed in an opening 31 in the body Nl. This shear pin 36 is of such strength as to prevent forward movement of the barrel I9 by any blows or shocks which might be applied to the gun body I0 during the ordinary handling ofthe same or such as might result froml adropping of the gun body I0. However, the strength of the shear pin 36 is such that it will be sheared by the explosive force applied to the rear end of the barrel I9 when the primer cord I2 is exploded'.

In the ordinary practice of the invention, a propelling charge or powder 22 is employed which is readily exploded by forward movement of the barrel I9 as previously described herein. However, the` invention comprehends the use of auxiliary igniting means in association with the powder charge, so as to assure ring of the powder charge under all circumstances, including the use of an explosive substance which is not fired by compression or where a primer cord is employed which has reduced explosive effect so that the barrel I9 is not driven forwardly with great force. In Fig. 4 I have shown a form o1' my invention, wherein an ignition means 4l is disposed in the gun barrel I8 behind the projectile 23. This igniting means may consist of a pressurefired fuse or cap. or it may consist of an air-filled chamber formed by a. wall 4| of relatively soft material so that it will collapse when the barrel I9 is driven forwardly, thereby compressing the gas within the chamber of the igniting means 49 so as to raise it to ignition temperature, such gas, at ignition temperature, passing through an opening 42 in the wall 4I into the powder charge 22, igniting such powder charge.

In the forms of the invention herebefore shown, the holding member 28 is threaded into the threaded opening 21 of the retainer 24, the purpose of this threaded connection being to prevent inward movement of the holding member 28 by liquid pressure encountered in the well. When the gun is employed in a dry' well, this threaded connection between the member 28 and the'retainer 24 need not be used, but, as shown in Fig. 5, the retainer 24 may have an unthreaded opening 21' to receive the forward portion of the holding member 28, and the holding member 28 may be provided -with an annular shoulder 50 engaging the retainer 24 so as to limit outward movement of the holder 28. f

I claim as my invention:

1'. In a gun, the combination of: a gun barrel having a transverse wall and being adapted to receive therein a projectile anda powder charge behind said projectile, said barrel being supported so that it may have forward movement; a holding member projecting into the forward end of said barrel and engaging said projectile so as to prevent its forward movement; and means for moving said barrel forwardly s o as to compress the powder charge between said transverse wall and the rear end of said projectile and-cause ignition of the same.

2. In a gun, the combination of a gun barrel having a transverse wall and being adapted to receive therein a projectile and a powder charge behind said projectile, said barrel being supported so that it may have forward movement; a holding member projecting into the forward end of said barrel and engaging said projectile so as 'to prevent its forward movement; and means to apply an explosive force for moving said barrel forwardly so as to compress the powder charge between said transverse wall and the rear end of said jectileand cause ignition of the same.

3. In a gun, the combination of: a gun barrel having a transverse wall and beingadapted to receive therein a projectile and a powder charge behind said projectile, said barrel being supported so that it may have forward movement; sealing means on said holding member for preventingI entry of fluid into said powder charge; a holding member projecting into the forward end of said barrel and engaging said projectile so as to prevent its forward movement; and means for moving said barrel forwardly so as to compress the powder charge between said transverse wall and the rear end of said projectile and cause ignition of the same.

4. In a gun having means for producing forward movement of its gun barrel, the combina-'- tion of: a gun body having a chamber with an external opening; va barrel axially movable in said chamber, the forward end of said barrel facing said opening of said chamber, said barrel being adapted to receive a projectile and an explosive charge behind said projectile; and means supported in said chamber having a holding member projecting into saidbarrel to control forward movement of said projectile so that when said barrel is moved forwardly relatively to said projectile, a compressive ignition elect will be applied to said explosive charge.

5. In agun, the combination of: a gun body having a chamber with an external opening; a barrel axially movable in said chamber, the forward end of said barrel facing said opening of said chamber, said barrel being adapted to recieve a projectile and an explosive charge behind said projectile; means supported in said chamber having a holding member projecting into said barrel to control forward movement of said projectile -so that when said barrel is moved forwardly relatively to said projectile, a compressive ignition effect will be applied to said explosive charge; and means for supporting an explosive so that force from the explosion thereof will produce forward movement of said barrel.

6. In a gun having means for producing forward movement of its gun barrel, the combination of: a gun body having a chamber with an external opening; a barrel axially movable in said chamben/the forward end of said barrel facing said opening of said chamber, said barrel being adapted to receive a projectile and a propelling charge behind said projectile; a retainer securable Iin the opening of said chamber for limiting forward movement of said barrel; and a holding member projecting from said retainer into said barrel to control forward movement of said projectile when said' barrel is moved for- Wardly.

7. In a gun having means for producing forward movement of its gun barrel, the combination of z ya gun body having a chamber with an external opening; a barrel axially movable in said chamber, the forward endvof said barrel facing said opening of said chamber, said barrel being adapted to receive a projectile and a propelling charge behind said projectile; a retainer securable inthe opening of said chamber for limiting forward movement of said barrel; a holding member projecting from said retainer into said barrel to control forward movement of said projectile when said barrel is moved forwardly; and means on said holding member for seaLng the outer end of said barrel.

8. In a gun having means for producing forward movement of its gun barrel, the combination of: a gun body having a chamber with an external opening and having a recess for an explosive communicating with the rear end of said chamber; a'barrel axially movable in said chamber, the forward end of said barrel facing said opening of said chamber, said barrel being adapted to receive a projectile and a propelling charge behind said projectile; a retainer securable in the opening of said chamber for limiting forward movement of said barrel; a holding member projecting from said retainer into said barrel to control forward movement of said projectile when said barrel is moved forwardly; and means on said holding member for sealing the outer end of said barrel.

JAMES O. TOW.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 2,755 Great Britain Oct. 13, 1862 

